Indian Space Research Organisation is using the most powerful configuration of its rocket PSLV to launch a communication satellite from Sriharikota on July 15 as it braces for the nearly Rs. 200 crore mission.

Itâ€™s only for the second time ever that a Polar Satellite Launch Vehicle is being used to loft a communication satellite, the first one being Kalpana-1 in 2002.

Bangalore-headquartered ISRO opted for this step as there is a large unfulfilled and pressing demand for communication transponders.

â€œBut we wanted to create (transponder) capacity at the earliest. Thatâ€™s why we used the PSLV for the purpose (of launching a communication satellite), and achieve whatever is possible...best possible by a PSLV with XL configuration. Thatâ€™s the most powerful configuration,â€ ISRO Chairman K. Radhakrishnan told PTI in Bangalore.

The GSAT-12 â€œfast-trackâ€ satellite with a mass of 1410 kg, has 12 Extended C-band transponders. It is slated to be injected into space by PSLV-C17 after the launch from Sriharikota spaceport slated between 16.48 hours and 17.08 hours on July 15.

Similar PSLV, with extended strap-ons, was used for Indiaâ€™s Chandrayaan-1 mission.

On the PSLV-C17/GSAT-12 mission cost, Mr. Radhakrishnan said, â€œLaunch vehicle of PSLV of XL-class will cost about Rs 100-Rs 110 crore, and GSAT-12 will be about Rs 80 crore. The life of the satellite will be about 7-8 years.â€ Mr. Radhakrishnan said in the beginning of the 11th plan, ISRO had 211 transponders, and the target then set was to take it to almost 500 by March 2012, which is end of the plan period.

But except for 24 transponders added by GSAT-8 which was operationalised recently, ISRO had not been able to enhance these numbers since September 2007.

â€œDuring the period, most of our satellites have either completed their normal life or there were premature terminations,â€ he said. â€œSo, this resulted in the 211 becoming 175 now. There is a lot of unfulfilled demand to be met.â€ To meet this growing demand, Bangalore-headquartered ISRO is building GSAT-10 with 36 transponders and it would be launched by Arianespace from Kourou in French Guiana during March-April next year.

â€œWe are also building another satellite GSAT-7 that will have a few more transponders,â€ Mr. Radhakrishnan added.

With the 53-hour countdown for the launch of the Polar Satellite Launch Vehicle (PSLV-C17) commencing at 11.48 a.m. on Wednesday, the stage is set for the rocket's lift-off from Sriharikota at 4.48 p.m. on Friday.

The PSLV-C17 will put in orbit communication satellite GSAT-12, which weighs 1,410 kg. It is a more powerful version of the standard PSLV, called PSLV-XL that will put the satellite in orbit after a 20-minute flight.

â€œThe countdown is going on satisfactorily,â€ said P.S. Veeraraghavan, Director of Vikram Sarabhai Space Centre (VSSC) in Thiruvananthapuram, from Sriharikota on Wednesday. The launch window is between 4.48 p.m. and 5.08 p.m. â€œWe will use the earliest opportunityâ€ at 4.48 p.m. for the rocket's ignition, he said. The four-stage PSLV was built by the VSSC.

This is the second time that a powerful PSLV-XL version will lift off from the second launch pad at Sriharikota. It was earlier used to put Chandrayaan-1 into orbit on October 22, 2008. While the six strap-on booster motors of the standard version of the PSLV carry a total of nine tonnes of solid propellants, the strap-on motors in the XL version are powered by a total of 12 tonnes of fuel.

â€œThis is [also] the second time that a PSLV is being used to put a satellite in a geo-synchronous transfer orbit (GTO),â€ said Mr. Veeraraghavan. It was earlier used on September 12, 2002 to put Kalpana, a weather satellite, in GTO.

Raising the apogee

In fact, the PSLV-C17 will put GSAT-12 in a sub-GTO with a perigee (nearest point to the earth) of 284 km and an apogee (farthest point from the earth) of 21,000 km. After it is put in a sub-GTO, commands will be given to the liquid apogee motor (LAM) on board the satellite to boost the apogee to 36,000 km. After it is done, commands will be given to boost the perigee from 284 km to 36,000 km.

â€œFor the first time, in our communication satellites, we are raising the apogee from 21,000 km to 36,000 km in two stages. This is a crucial manoeuvre. To raise the apogee, you have to fire the LAM when the satellite is in its perigee. So the LAM firing is a challenge,â€ said a satellite technologist of the Indian Space Research Organisation (ISRO). The satellite will thus reach a circular geo-stationary orbit of 36,000 km.

Advanced mission computer

â€œA significant feature of the PSLV-C17,â€ said Mr. Veeraraghavan, â€œis that it will use an advanced mission computer with indigenous processors. The ISRO built the computer. We also built our own processors. The advanced mission computer will be used for navigation, guidance and controllingâ€ the rocket. The ISRO earlier used imported processor chips in the PSLV missions. In the PSLV-C12 mission in 2009, it used one chain of imported processors and another chain of indigenous processors. â€œIn this mission, both the prime and the redundant chains have indigenous processors,â€ Mr. Veeraraghavan said.

The GSAT-12, with 12 extended C-band transponders, will be used for tele-medicine, tele-education, telephone and various other communication purposes.

This is the 19th PSLV mission, out of which 17 have been successful in a row. The PSLV-C17 weighs 310 tonnes and is 44 metres tall.

The Launch Authorisation Board (LAB) for PSLV-C17/GSAT-12 mission, which met on July 12, 2011 at Satish Dhawan Space Centre - SHAR, Sriharikota has cleared the launch of PSLV-C17 at 16:48 hrs (IST) on Friday, July 15, 2011.

The 53 hour countdown commenced at 11:48 hours on July 13, 2011. During the Countdown, propellant-filling operations of the liquid propellant second stage (PS2) and fourth stage (PS4) of the launch vehicle will be carried out. Mandatory checks on the launch vehicle and spacecraft including charging of batteries and pressurisation of propellant tanks will be performed. Readiness of various ground systems such as tracking radar systems and communication networks will also be checked.

PSLV-C17 will launch GSAT-12 satellite into a sub-Geosynchronous Transfer Orbit of 284 km perigee and an apogee of 21,000 km. GSAT-12 communication satellite weighing 1410 kg with 12 Ext-C Band transponders will augment the communication services in the country.

The countdown for the launch of the Polar Satellite Launch Vehicle (PSLV - C17) at Sriharikota is on without any holds and if the situation holds good, the rocket will lift off at 4.48 p.m. on Friday and put in orbit communications satellite GSAT-12.

The 53-hour countdown, which began at 11.48 a.m. on July 13, â€œis progressing smoothly without any problem,â€ spokesman for the Indian Space Research Organisation (ISRO) S. Satish said on Thursday. â€œAll the mandatory checks on the vehicle and the satellite have been completed successfully.â€

The filling of the second and fourth stages of the rocket with liquid propellants was in progress. The first stage, the third stage and six strap-on booster motors strung around the first stage use solid fuel, he pointed out.

After the failure of two Geo-synchronous Satellite Launch Vehicle (GSLV) flights in April, 2010 and December 2010 to put GSAT-4 and GSAT-5P respectively in orbit, the ISRO is in dire need of transponders to meet the burgeoning needs of communication in the country.

So the ISRO has resorted to the use of its trusted workhorse, the PSLV, to put GSAT-12 in orbit.

CHENNAI: The Indian Space Research Organisation (Isro) on Friday successfully launched its Polar Satellite Launch Vehicle (PSLV- C17) from the Satish Dhawan Space Centre at Sriharikota, 100 km north of Chennai, carrying to space GSAT-12, a communication satellite. This is the 18th successful launch of PSLV.

The majestic launch vehicle lifted off from Sriharikota at 4.40 pm and within a few seconds disappeared into the clouds. Thirty minutes later, it injected the satellite into an orbit with a perigee (closest point to earth) of 284 km and an apogee (farthest point) of 21,000 km.

"PSLV-C17 launch has been a success," Isro chairman K Radhakrishnan said. "We have achieved an orbit just 8 km away from the one planned. In the next half an hour we will get information on the health of the satellite."

GSAT-12, weighing 1,410 kg at lift-off, is configured to meet the country's growing demand for transponders in a short turnaround time. It will boost television broadcasting and various other communication services like tele-education, telemedicine and village resource centres.

PSLV-C17, which marked the 19th flight of the Isro's workhorse, was similar to the one used for the Chandrayaan-1 mission on October 22, 2008, with six extended solid strap-on motors. The Indian National Satellite (Insat) system, established in 1983, is one of the largest domestic communication satellite systems in the Asia Pacific region.